It has been found that when many fluids are exposed to a variety of environmental conditions, their physical properties change. These changes occur primarily in two areas. The chemical composition of the fluid itself may be changed through the application of heat, pressure, chemical reactions with other fluids, or air-oxidation. In addition, the fluid may be contaminated by other fluids, contaminants or particulate matter from other sources, which, although not chemically combining with the fluid, affects the fluid's ability to function as it was intended, which function is best accomplished by a pure fluid.
Exemplary of such a fluid susceptible to both of these changes is lubricating motor oil used in an internal combustion engine. A pure motor oil is ideally suited for providing lubrication within the internal combustion engine. However, due to the high temperature necessarily present in such engines, breakdown of the molecular structure of the motor oil takes place with resulting loss of lubricating ability. The remnants of the broken down motor oil molecules remain in the motor oil as contaminants. In addition, other contaminants such as carbon deposits and fine metal particles which result from the operation of the engine are also introduced into the motor oil thereby contaminating it. Other contaminants are introduced into the motor oil such as water or anti-freeze from the engine cooling system. Dust particles, introduced into the engine with the air through the carburization system, are blown past compression and oil rings into the engine crank case from the combustion chamber during the compression stroke of the pistons.
Given time, the breakdown of pure motor oil and the introduction of contaminants into the motor oil renders the motor oil unable to effectively perform its job of lubricating the engine parts. When this occurs, the used motor oil should be replaced with new motor oil. The amount of time it takes for motor oil to reach this condition depends on a variety of factors including the strain put on the engine, the adequacy of cooling measures related to the engine, and external environment of the engine during operation.
Many fluids have additives added to them to enhance their inherent capabilities. These additives result in variant chemical and light absorbing properties. Examples of such chemicals are the various types of fuel enhancers used in the automotive fuel industry. For example, the introduction of ethanol, a common additive in many fuels, radically changes in a predictable way the overall light absorption properties of the resultant ethanol gasoline mixture.
The instant invention was designed to detect both when a fluid, either by breakdown or by contamination, has moved outside of an acceptable range of operating parameters, and also when the presence of certain additives are present in the tested fluid.
In researching these two problems, it was discovered that the light absorbing properties of a fluid is altered by the breakdown of the fluid itself, or by the introduction of contaminants or additives into the fluid. It was also discovered that breakdown or contamination of the fluid affects the light absorbing characteristics of the fluid by different amounts for different wavelengths of light. In particular, it was found that a ratio established by passing light of various wavelengths through the fluid to be tested and then detecting and comparing the strength of the light after passing through the fluid indicates the condition of the fluid related to the above mentioned detrimental characteristics. In particular, it was found that when the ratio for the preselected wavelengths reaches a certain ratio, the fluid is no longer within acceptable standards set for the fluid. With this in mind, the instant invention was motivated.
Because the change in fluid takes place within the environment where the fluid is found and because change in the fluid is a continuous process, the fluid should be tested continuously while it is being used in order to immediately detect detrimental changes. In this context, it is preferable to non-destructively, continuously test the fluid so that the testing process itself does not contribute to the breakdown and contamination problems of the fluid. Therefore, the light of various wavelengths should be introduced to the fluid in such a way that it can continuously and non-destructively interact with the fluid while helping to determine the condition of the fluid.